Radio apparatus



30, w. J. LARKIN. JR 2.209,626

, RADIO APPARATUS Filed Sept. 11, 1939 A 1&2

) Inven'l'or. 4/ 44in i. $4253 Patented July so, 1940 UNITED STATES PATENT OFFICE mmo APPARATUS I 'William J. Larkin, 'Jr., Lynnfield, Mass., asslgnor to National Company,. Inc., Maiden, Mass., a corporation of Massachusetts Application September 11, 1939, Serial No. 294,260

2 Claims.

comprises an improved variable condenser particularly adapted 'to bemounted on an improved support.- With the tremendous increase in the useof mobile transmitting and receiving apparatus in police cars yachts, automobiles, and aircraft has come a demand for compactness and rigidity. Designers of radio equipment are required to space the various elements closely together and to mount them rigidly in place in order to avoid short circuits and changes in distributed capacities which might otherwise result from shocks and the motion to which the apparatus is subjected. It has been the practice to secure radio frequency chokesand small condensers to the chassis of a, radio set merely by the lead wires which are soldered to the various connected elements, a practice which results in the disadvantages suggested in the foregoing paragraph. The most important object of my invention is to provide means for detachably but rigidly securing chokes or condensers to the chassis or panel of a radio set, so that shocks due to movement of the set 5 will not change the position of the mounted elements.

An important feature of my invention resides in a stand-off insulator provided with means for attachment to a panel or chassisand to -a a choke or condenser.

Another feature of my invention consistsin a novel variable condenser so constructed as to take up very little room" and which maybe located closely adjacent a. tube or other element so that the leads therefrom are of the minimum length.

A further featur'eofmy invention resides in a supportfcore, and caps constructed and arranged so'that they may be cooperatively assembled in the organization of a choke coil or a condenser as desired.

These. and other objects and features of my invention will be more readily understood and appreciated from the following detailed description of preferred embodiments thereof, selected for purposes of illustration and shown in theaccompanying drawing, in which: I

Fig. 1 is an exploded view in perspective of a condenser and support therefor,

Fig. 2 is a view in cross section of a condenser and its support also suggesting 'its location adjacenta vacuum tube, and;

Fig. 3 is a view-in side elevation of a radio frequency choke constructed according to the invention. 1

, This invention relates to radio apparatus andnected to the lower lead wire.

condenser.

The improved support constructed according to my invention and as shown in the drawing comprises a. frustro-conical stand-off insulator ID of p'rocelain, steatite, or other good insulating material. The insulator, l0 as shown in Figs. 1 5 and 2 is axially recessed and tapped at the topand bottom and is adapted to support a condenser. The body of the condenser is a hollow elongated core 12 of porcelain or other dielectric material which has metal caps i4 and I8 die cast 1 on both ends, a washer l3 of phenolin resin or similar material being pressed in the lower end of the core l2 to prevent metal from entering the interior thereof during the die casting opera- .tion. The bottom cap H has an integral short 15 screw or stem 18 which'threads into the tip of the insulator, l0, and the upper cap I6 is internally threaded to receive a long screw 22 having a lock nut 20 and a knurled head. Integral with the bottom cap II is an elongated metal sleeve 2| 20 which surrounds the core i2. The metal of the caps and the sleeve is a good conductor of electricity, and lead wires 26 are secured to the caps II and IS. The screw 22 makes good contact with the cap l6 and thus with the upper lead 25 wire 26, while the sleeve 24 is electrically con- It will be apparent that the sleeve 24, the core l2, and the screw 22 form respectively the stator, dielectric, and

rotor of a small condenser wherein the capacity 30 chassis or a panel. It will be apparent that the condenser takes upvery little space on the panel or chassis and that it is held securely in position 40 to withstand shocks.

The condenser on its support [0 is particularly well adapted for use as a neutralizing condenser in. the push-pull circuit of a radio transmitt'ern In Fig. 2 a vacuum tube 22 is shown (diagrammatically) in its socket 34 adjacent the The upper lead wire 26 goes directly from the condenser to the grid cap 36 of the tube, 32 while the lower lead 26 goes to one of the contact points 38 of the socket 34. In high frequency radio apparatus it is highly important offers important advantages in radio construction. s

In Fig. 3 my invention is shown embodied in a radio frequency choke. In this example it includes a frustro-conical insulator 40 secured to the panel or chassis 42 by a screw 44. The choke consists of a core 46 of steatite or other suitable insulating material which is secured to the top of the insulator 40 by means of a screw 48 integral with a metal cap 50 which is secured to the lower end of the core 46. A coil 54 is wound in four sections around the core 46 and its ends are soldered to the caps 50 and 52, which also carry leadwires56. Like the,condenser, the choke may be mounted vertically or horizontally near the elements to which it' is to be connected. It

i will be obvious that the coil of the choke is del- 35 shown is only one of many types commonly used and which maybe mounted in. similar fashion.

icate and my novel support has the advantage of holding the choke rigidly so that it cannot come into contact with elements in the set which might disturb the winding or break the wire.

It should be pointed out that many of the elements of' the choke are interchangeable with those of the condenser. The stand-oil? insulator, 25

invention includes within its scope the modifications which may be, necessary or desirable when incorporating the choke or condenser into radio sets of various designs. Furthermore the choke Having thus disclosed my invention and described in detail specific embodiments thereof I claim as new and desire'to secure bY'IJClFlSGI'S I Patent of the United States;

1. A variable condenser comprising an elongated core of insulating material having an axial passage therein, a metal capsurrounding one end of the core and having a screw threaded aperture co-axial with the passage in the core,

an insulating disc closing the other end of the passage in the core; a solid cap surrounding the closed end of the core, a cylindrical sleeve integral with the solid cap and surrounding a portion of the core, a threaded mounting stem in-' 'tegral with the solid-cap, andan elongated threaded rod disposed in the passage in spaced relation with the. wall thereof and movable axially therein. a

' 2. A variable condenser comprising'an elongated 'coreof insulating material having an axial passage therethrough, a metal cap surrounding one end of said core'fand having a screw threaded aperture therein smaller in diameter than the diameter of the axial passage, a'solid metal cap *surrounding the other end of the core, an insulating disc disposed in, the .end of said passage adjacent the solid metal cap, a cylindrical sleeve integral with the solid cap and surrounding only a portion of the core, a screw threaded mounting stem also integral with the solid cap, and an elongated screw threaded in the apertured cap and movable axially in the passage in the core.

WILLIAM J. LARKIN, JR. 

